1. Field of the Invention
The present invention relates to a developing apparatus using a bicomponent developing material consisting of a toner and a magnetic carrier and, more particularly, to a developing apparatus which is advantageously applicable to transfer-type electrostatic copying apparatus and laser printers.
2. Description of the Prior Art
A typical prior art arrangement is shown in FIG. 1. A shaft 4 is disposed between a developing roller 2 and a stirring roller 3 in a developing tank 1. The shaft 4 has a diameter of about 3 mm extends and the axial direction of the rollers 2, 3 so that the developing roller 2 can be cleaned of any remaining developing material through scraping action of the shaft 4 and so that the shaft 4 can aid in stirring. In FIG. 1, shown by numeral reference 5 is a toner concentration sensor, numeral reference 6 is an agitating roller, numeral reference 7 is a roller for supplying toner, and numeral reference 8 is a cylindrical photosensitive drum.
Recently, in the art, much attention is directed toward size reduction of the developing tank. As a result, the distance between the centers of the developing roller 2 and the stirring roller 3 tends to become smaller, so that their respective outer peripheries are brought closer to each other. In such case, the developing material is often transported irregularly due to its periodic longitudinal movement by the action of the stirring roller 3, which poses a problem that irregular shading occurs in copy images, which is largely attributable to the periodic movement of the developing material.